The present invention relates to ball valves, and in particular to ball valves for use in conjunction with high pressure or high temperature fluid flow. The inventive ball valve allows easy and simple removal and replacement of a ball member and seat ring, when required, without disassembly of a bonnet, a ball cage, a top cap assembly or a bottom cap assembly associated with the valve.
The valve art is highly developed and includes a wide variety of ball valves. Some of the major advances in ball valves are exemplified by the art disclosed in various United States Patents, for example: U.S. Pat. Nos. 2,629,578; 3,264,718; 3,749,355; and 3,779,508, which are related in a broad sense to the valve disclosed herein.
Conventional ball valves function well in controlling fluid flow rate and stopping flow therethrough when desired. Such valves generally comprise a valve body having a horizontal channel forming a venturi and a vertical passageway intersecting the horizontal flow channel near the center of the valve. A ball cage, containing a ball member, is reciprocably mounted within the vertical passageway and, when motivated through the passageway, permits selective flow through the valve. As the ball cage is lowered, the ball member seats against a seating ring in the flow channel, thus closing the valve. Raising the ball cage functionally moves the ball away from the valve seat and opens the valve.
A major problem with such ball valves is that the ball member and the valve seat must be periodically examined and replaced. In conventional ball valves using a movable ball cage, this requires a partial disassembly as much of the valve, possibly including the valve bonnet and seal, the cage and cage operating assembly, a top or bottom cap and seal, and any electronic components connected to the valve. Although such a disassembly for maintenance and repair does not necessarily involve a disconnection of the valve body from a fluid flow line, it does require a significant number of skilled technicians, and thus, may be very expensive and time consuming.
Additionally, it has proven to be difficult to reassemble such a ball valve in a manner precluding leaks and permitting efficient operation once the major components have been disassembled. Therefore, conventional ball valves such as those described in U.S. Pat Nos. 3,749,355 and 3,799,508, although effective, can be very difficult and expensive to maintain. Such valves are also rather complex in design and are therefore often relatively very expensive to originally purchase.